Chapter 18. The Sexual Systems
18.0 Introduction
Chapter Objectives
By the end of this chapter, you will be able to:
- describe the anatomy of the reproductive systems, including their accessory structures;
- explain the role of hypothalamic and pituitary hormones in reproductive function;
- describe the development and maturation of the sex organs and the emergence of secondary sex characteristics during puberty;
- explain the events of the menstrual and uterine cycles; and
- trace the path of a sperm cell from its initial production through the fertilization of an oocyte.
Small, uncoordinated, and slick with amniotic fluid, a newborn encounters the world outside of the womb. We do not often consider that a child’s birth is proof of the healthy functioning of reproductive systems. Moreover, endocrine systems had to secrete the appropriate regulating hormones to induce the production and release of unique male and female gametes, reproductive cells containing genetic material (one set of 23 chromosomes). Reproductive behavior or medical innovation had to facilitate the transfer of male gametes (the sperm) to the female gamete, the oocyte (egg). Finally, combination of the gametes (fertilization) had to occur, followed by implantation and development. In this chapter, you will explore the reproductive systems, whose functioning can culminate in the powerful sound of a newborn’s first cry.
Note: The terms sex and gender are often used interchangeably, but these terms have different contexts and meanings. Gender is socially constructed and operates as a way to identify and categorize certain behavioral, cultural, and psychological traits as belonging to specific groups of people. Sex is a biological construct that refers to the structural, functional, and behavioral characteristics of living beings determined by sex chromosomes. Although the sexual system is often described as a binary of male and female, in reality there is a spectrum of anatomical and chromosomal variation found in the human population, including intersex individuals as well as genitalia considered ambiguous at birth. In addition, sexual anatomy has a long history of surgical intervention such a circumcision, vasectomy, tubal ligation, and sex reassignment surgery. Sexual anatomy has typically been described using only heterocentric language and binary sexual identity, with an assumption that sex only occurs between a cisgender man and cisgender woman for the purpose of reproduction, making it one of the least inclusive and representative topics found in anatomy textbooks. In this chapter, we attempt to present anatomy and physiology in ways that incorporate more lived experiences, rather than only what exists at the binary extremes.
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